Hydrogen storage hydride electrode materials

ABSTRACT

Four groups of advanced hydrogen hydride storage and hydride electrode materials, consisting of two common elements, titanium and nickel. In the first group of materials, zirconium and chromium are added with the common elements. The second group of materials contain three additional elements in addition to the common elements, namely, chromium, zirconium and vanadium. The third group of materials contain also, in addition to the common elements, zirconium and vanadium. The fourth group of materials adds manganese and vanadium with the common elements. The preparation methods of the materials, as well as their hydride electrode are disclosed. Electrochemical studies indicate that these materials have high capacity, long cycle life and high rate capability.

.Iadd.This application is a continuation of Ser. No. 438,340, filed Nov.16, 1989, now abandoned, which is a reissue application of Ser. No.122,042, filed Nov. 17, 1987, U.S. Pat. No. 4,849,205. .Iaddend.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to hydrogen storage materials and theirelectrochemical application. More particularly, this invention relatesto the composition of novel materials for rechargeable hydride electrodematerials. This invention further relates to a simple but effectivemethod to determine a multi-component alloy as a potential candidate forhydride electrode applications.

2. Description of the Prior Art

Hydrogen can be stored in a heavy cylinder at high pressure as a gas atroom temperature, or it can be stored in a well insulated container atlow pressure as a liquid at ultra low temperature. The high pressurestorage method involves significant safety problems, and relativelylittle hydrogen can be stored in a given volume of container vessel. Theultra low temperature storage method involves a significant waste ofelectricity to power cryogenic liquefaction devices, and, because ofevaporation, the hydrogen cannot be stored indefinitely.

A preferable way to store hydrogen is to use a solid material which canabsorb hydrogen in a reversible manner. This process is known ashydriding. Two examples of hydriding processes are:

    M(s)+1/2H.sub.2 (g)→MH(s)                           (1)

    M(s)+1/2H.sub.2 O+e.sup.-- →MH(s)+OH.sup.--         (2)

where M(s) is the solid hydrogen storage material, MH(s) is the solidhydride, e⁻⁻ is an electron and OH⁻⁻ is the hydroxyl ion. Equation (1)is a solid-gas reaction process which can be used to store thermalenergy. Equation (2), on the other hand, is an electrochemical reactionthat can be used to store electrical energy. In both equations, hydrogenis stored during a charge reaction and is released during a dischargereaction.

Not every metal alloy can be used in the above hydriding process. It isalso the case that not every metal alloy that can be utilized in thesolid-gas reaction (Eq. 1) can be used in the electrochemical reaction(Eq. 2). For example, the hydrogen storage materials: Ti-Zr-Mn-C-Valloys, disclosed in U.S. Pat. No. 4,160,014 are not readily suitablefor electrochemical reactions, as for example those involved in abattery application. Another example of hydrogen storage materials isgiven in Japanese Patent Sho 55-91950 which discloses alloys with thefollowing composition formula: (V_(1-x) Ti_(x))₃ Ni_(1-y) M_(y), where Mequals Cr, Mn, Fe, and where x and y are defined by: 0.05≦x≦0.8 and0≦y≦0.2. These materials restrict the amount of Ni+M equal to 25 atomicpercent with less than 5 atomic percent of M, and the amount ot Ti+Vequal to 75 atomic percent. As a result, in addition to the potentialcorrosion problem adduced from using these materials, the hydrides ofthese materials are either very stable at ambient temperature or are ofhigh cost. Consequently, these materials are not readily .[.useable.]..Iadd.usable .Iaddend.for electrochemical applications.

Among the many hydride materials that have been developed, only a few ofthem have been tested electrochemically. Examples of such research areU.S. Pat. Nos. 3,824,131, 4,112,199, and 4,551,400. The hydrideelectrode materials invented primarily by the present inventor anddisclosed in U.S. Pat. No. 4,551,400 have superior properties ascompared to the hydride electrode materials described in the otherpatents hereinabove cited. The materials disclosed in the U.S. Pat. No.4,551,400 are grouped as:

    .[.TiV.sub.1-x Ni.sub.x .]. .Iadd.TiV.sub.2-x Ni.sub.x .Iaddend.where 0.2≦x≦1.0;                                  (a)

    Ti.sub.2-x Zr.sub.x V.sub.4-y Ni.sub.y, where 0≦x≦1.50, 0.6≦y≦3.50,                                 (b)

which can be rewritten as .[.Ti_(1-x), Zr_(x), V_(2-y), Ni_(y),.]..Iadd.Ti_(1-x') Zr_(x') V_(2-y') Ni_(y'), .Iaddend.

where 0≦x'≦0.75, 0.3≦y'≦1.75; and

    Ti.sub.1-x Cr.sub.x V.sub.2-y Ni.sub.y, where 0.2≦x≦0.75, 0.2≦y≦1.0.                                  (c)

These materials are all limited to the pseudo TiV₂ type alloys with thefollowing composition restriction:

Group (a): Ti=33.3 atomic %, V+Ni=66.7 atomic %;

Group (b): Ti+Zr=33.3 atomic %, V+Ni=66.7 atomic %; and

Group (c): Ti+Cr=33.3 atomic %, V+Ni=66.7 atomic %.

This restriction results in all these materials having one or severalweaknesses, especially high cost, short life cycle, and low capacity, aswell as in some cases poor rate capability.

A good hydrogen storage material of the class described suitable forelectrochemical applications has not been reported to date in thescientific literature, as well as Letters Patent. Particularly there hasbeen no disclosure of how to provide a simple qualitative approach fordeveloping or optimizing hydride materials for storing hydrogen as wellas for hydride electrodes. As a result, the common method has been oneof a trial-and-error, which has resulted in the expenditure ofconsiderable wasted time, money and human resources.

Consequently, which is needed is a good hydrogen storage electrodematerial, having at the minimum the following properties:

Excellent hydrogen storage capacity;

superior electrochemical catalyst for hydrogen oxidation;

high hydrogen diffusion rate;

suitable hydrogen equilibrium pressure; and

reasonable cost.

To fit the above restrictions, the present invention provides, throughthe application of thermodynamics, kinetics and electrochemistry, amethod for selecting a good hydride candidate suitable forelectrochemical applications. More particularly, the composition ofadvanced hydride electrode materials and the methods of theirfabrication are disclosed herein.

SUMMARY OF THE INVENTION

The present invention discloses the following materials, represented byformulae, for hydrogen storage and hydride electrode applications.

    .[.Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x,.]. .Iadd.Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x H.sub.y or Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d H.sub.y .Iaddend.

where M equals any of Al, Si, V, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.4,0.1≦b≦1.3, 0.24≦c≦1.95, 0.1≦d≦1.4, and a+b+c+d=3, and 0≦x≦0.2 .Iadd.andy>0.Iaddend..

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earthmetals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.3,0.1≦b≦1.2, 0.1≦c≦1.3, 0.2≦d≦1.95, .[.0.4≦a+b+c+d≦2.9.]..Iadd.0.5≦a+b+c+d≦2.9.Iaddend., 0≦x≦0.2, and for x=0 and b=0.5, thena+c≠0.5.

    Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c M.sub.x,

where M equals any of Al, Si, Cr, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, b, c, and x are defined as: 0.1≦a≦1.3,0.1≦b≦1.3, 0.25≦c≦1.95, 0≦x≦0.2, and 0.6≦a+b+c≦2.9; for x=0 then a+b≠1and 0.24≦b≦1.3.

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x,

where M equals any of Al, Si, Cr, Fe, Co, Cu, Nb, Zr, Ag, Pd, and rareearth metals, and were a, b, c, d, and x are defined by: 0.1≦a≦1.6,0.1≦b≦1.6, 0.1≦c≦1.7, 0.2≦d≦2.0, a+b+c+d=3, and 0≦x≦0.2.

The materials disclosed by the present invention may be prepared byelectric arc, induction or plasma melting under inert atmosphere. Thepresent invention also provides methods of storing hydrogen by thematerials disclosed.

The present invention further discloses a general method to develop apotential multicomponent alloy A_(a) B_(b) C_(c) . . . for hydrogenstorage and rechargeable hydride electrode applications. This methodconsists of the following two steps:

Step 1: Let the candidate alloy A_(a) B_(b) C_(c) . . . contain at least5 mole percent, but less than 65 mole percent, of nickel metal in thecomposition, preferably, 15 to 45 mole percent of nickel; and

Step 2. Set the proper numbers of a, b, c, . . . in the alloy A_(a)B_(b) C_(c) . . . such that it has a calculated heat of hydrideformation, H_(h), between -3.5 and -9.0 Kcal/mole H, preferably -4.5 to-8.5 Kcal/mole H. The equation for the H_(h) calculation is:

    H.sub.h =(aH.sub.h (A)+bH.sub.h (B)+cH.sub.h (C)+ . . . )/(a+b+c+ . . . )+K,                                                      (3)

where H_(h) (A), H_(h) (B), H_(h) (C), . . . are the heat of hydrideformation of the metals A, B, C, . . . , respectively, in Kcal/mole H,and where K is a constant related to the heat of formation of the alloyA_(a) B_(b) C_(c) . . . and the heat of mixing of hydrides of A, B, C, .. . The values of K are: 0.5, -0.2, and -1.5 for a+b+c+ . . . equal to2, 3, 6, respectively. However, for practical purposes, the value of Kcan be set to zero. The values of the heat of hydride formation of metalelements can be found elsewhere, exemplified by the following:

Mg: -9.0, Ti: -15.0, V: -7.0, Cr: -1.81, Mn: -2.0, Fe: 4.0, Co: 4.0, Ni:2.0, Al: -1.38, Y: -27.0, Zr: -19.5, Nb: -9.0, Pd: -4.0, Mo: -1.0, Ca:-21.0, and rare earth metals: -25.0, all in units of Kcal/mole H.

For the alloy with a+b+c+ . . . other than 2, 3, and 6, K can simply beset equal to zero, or the formula may be normalized to the nearestpseudo type and therefore its heat of hydride formulation can still beobtained by equation (3).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention discloses four main groups of materials which canserve as a hydride for reversible hydrogen storage applications, andmore particularly, can serve as a negative electrode active material for.[.elctrochemical applications..]. .Iadd.electrochemical applications..Iaddend.

The first group of materials contains titanium, zirconium, nickel andchromium. It may also include another element or elements such asaluminum, vanadium, manganese, iron, cobalt, copper, niobium, silicon,silver and palladium, or rare earth metals. The composition of an alloyin this group can be represented by the following formula:

    Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x,

where M equals any of Al, Si, V, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.4,0.1≦b≦1.3, 0.25≦c≦1.95, 0.1≦d≦1.4, a+b+c+d=3, and 0≦x≦0.2. Preferably,0.25≦a≦1.0, 0.2≦b≦1.0, 0.8≦c≦1.6, and 0.3≦d≦1.0.

The second group of materials of the present invention containstitanium, chromium, zirconium, nickel and vanadium. Another element orelements can be added, such as aluminum, silicon, manganese, iron,cobalt, copper, niobium, silver, palladium, or rare earth metals. Thecomposition of an alloy in this group is expressed by the followingformula:

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earthmetals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.3,0.1≦b≦1.2, 0.1≦c≦1.3, 0.2≦d≦1.95, .[.0.4≦a+b+c+d≦2.9.]..Iadd.0.5≦a+b+c+d≦2.9.Iaddend., 0≦x≦0.2, and for x=0 and b=0.5, thena+c≠0.5. Preferably, 0.15≦a≦0.1, 0.15≦b≦1.0, 0.2≦c≦1.0, 0.4≦d≦1.7, and1.5≦a+b+c+d≦2.3.

.Iadd.An alternative to the second group of materials is thecomposition: Ti_(a) Cr_(a) Zr_(c) Ni_(d) V_(3-2a-c-d) M_(x) wherein Mequals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earth metals,and where a, c, d, and x are defined by: 0.1≦a≦1.2, 0.1≦c≦1.2,0.2≦d≦1.95, 0.9≦2a+c+d≦2.8, and 0≦x≦0.2.

Another alternative is a composition of the formula: Ti_(a) Cr_(a)Zr_(1-2a) Ni_(d) V_(2-d) M_(x) where M equals any of Al, Si, Mn, Co, Cu,Fe, Nb, Ag, Pd, and rare earth metals, and where a, d, and x are definedby: 0.1≦a≦0.45, 0.25≦d≦1.95, and 0≦x≦0.2.

Another alternative is the following composition formula: Ti_(a) Cr_(a)Zr_(c) Ni_(2-c) V_(1-2a) M_(x) where M equals any of Al, Si, Mn, Co, Cu,Fe, Nb, Ag, Pd, and rare earth metals, and wherein a, c, and x aredefined by: 0.1≦a≦0.45, 0.2≦c≦1.2, and 0≦x≦0.2. .Iaddend.

The third group of materials described by the present invention containstitanium, zirconium, nickel and vanadium. Another element or elementscan be added, such as aluminum, silicon, manganese, iron, cobalt,copper, niobium, silver, palladium, or rare earth metals. Thecomposition of an alloy in this group is expressed by the followingformula:

    Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c M.sub.x,

where M equals any of Al, Si, Cr, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, b, c, and x are defined as: 0.1≦a≦1.3,0.1≦b≦1.3, 0.25≦c≦1.95, 0≦x≦0.2, and 0.6≦a+b+c≦2.9; for x=0 then a+b≠1and 0.24≦b≦1.3. Preferably, 0.15≦a≦0.8, 0.2≦b≦0.8, 0.5≦c≦1.5, and1.5≦a+b+c≦2.5.

.Iadd.An alternative composition formula is: Ti_(a) Zr_(y-a) Ni_(c)V_(3-y-c) M_(x) wherein M equals any of Al, Si, Cr, Mn, Fe, Co, Cu, Nb,Ag, Pd, and rare earth metals, and where a, c, x, and y are defined as:0.1≦a≦1.3, 0.2≦c≦1.95, 0≦x≦0.2, and 0.7≦y≦1.6. .Iaddend.

The fourth group of materials according to the present inventioncontains titanium, manganese, nickel, and vanadium. Another element orelements can be added, such as aluminum, silicon, iron, cobalt, copper,zirconium, niobium, silver, palladium, or rare earth metals. Thecomposition of an alloy in this group is expressed by the followingformula:

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x,

where M equals any of Al, Si, Cr, Fe, Co, Cu, Nb, Zr, Ag, Pd, and rareearth metals, and were a, b, c, d, and x are defined by: 0.1≦a≦1.6,0.1≦b≦1.6, 0.1≦c≦1.7, 0.2≦d≦2.0, a+b+c+d=3, and 0≦x≦0.2. Preferably,0.5≦a≦1.3, 0.3≦b≦1.0, 0.6≦c≦1.5, and 1.4≦a+b+c≦2.7.

The present invention also provides a simple method to select thecomposition of a multicomponent alloy for hydrogen storage andrechargeable hydride electrode applications.

The reaction mechanisms on a hydride electrode are very different fromthat of an .[.electrocatallytic electrode,.]..Iadd.electrocatalyticelectrode, .Iaddend.rode, such as those used for water electrolysis orfuel cells. A hydride electrode not only serves as an electrocatalystfor hydrogen oxidation (during discharge) and water electrolysis (duringcharge), but also serves as a medium for the storage and release ofhydrogen. Because of these dual functions, some researchers havesuggested the use of a surface coating to improve the surface catalyticproperty of a hydride electrode to boost the rate capability. However,this approach can only give a very limited improvement. The surfacecoating has a very limited domain, and can be easily destroyed byswelling and shrinking processes during the course of the charge anddischarge cycles due to the accompanying hydriding and dehydriding ofthe material during these cycles, respectively. The best way toguarantee a good rate capability of an electrode is to enhance theintrinsic property of a hydrogen storage alloy such that every part ofthe material body has good catalytic function in addition to hydrogenstorage function.

According to the present invention, the alloy A_(a) B_(b) C_(c) . . . ofA, B, C, . . . elements should contain at least 5 mole percent of nickelto have a resonable rate capability, but not contain more than 65 molepercent of nickel, to insure a reasonable amount of hydrogen storagecapacity. Preferably, the nickel content is in the range of between 15to 45 mole percent.

In addition to the restriction of nickel content, according to thepresent invention, the alloy should meet the hydrogen pressure and bulkdiffusion rate requirements setforth hereinabove. The material A_(a)B_(b) C_(c) . . . should have a calculated heat of hydride formation(i.e., partial molar heat of enthalpy of hydrogen), H_(h) in the rangeof between -3.5 and -9.0 Kcal/mole H. Preferably this heat, H_(h), isbetween -4.5 and -8.5 Kcal/mole H. The heat of hydride formation, H_(h),of an alloy A_(a) B_(b) C_(c) . . . can be calculated through thefollowing thermodynamic cycle: ##STR1## where H_(f) is the heat offormation of the alloy A_(a) B_(b) C_(c). . . , H^(m) is the heat ofmixing of hydrides AH, BH, CH, . . . , and each is with the respectiveheat of hydride formation H_(h) (i), i.e., H_(h) (A), H_(h) (B), H_(h)(C), . . . Kcal/mole H.

For a +b+c+ . . . =n, it is clear from the above thermodynamic cyclethat the heat of hydride formation of the alloy A_(a) B_(b) C_(c) . . ., H_(h), is:

    H.sub.h =(aH.sub.h (A)+bH.sub.h (B)+cH.sub.h (C)+. . . )/(a+b+c+. . . )-H.sub.f /(a+b+c+. . . )+H.sup.m.

The mixing of hydrides can be considered the mixing of metals withhydrogen as common species. This process is similar to the mixing ofbinary .[.fluorides, where the fluoride.]. .Iadd.fluorides, where thefluoride .Iaddend.ions are the common species. From knowledge of.[.flouride.]. .Iadd.fluoride .Iaddend.systems, the values of the heatof mixing of binary hydrides to form a relatively stable multicomponenthydride, should be between -2 and -5 Kcal/mole H, depending upon themetals used. Let H^(m) equal -2.5 Kcal/mole H. On the other hand, ingeneral, the heat of formation of a stable metal alloy, H_(f), is about-6.0±3.0 Kcal/mole alloy.

Comparing the values of H^(m) and H_(f), equation 3, above, can beobtained. Therefore, the heat of hydride formation, H_(h), of the alloyA_(a) B_(b) C_(c) . . . can be thereby calculated.

Thus, the steps 1 and 2 described above can be used to provide a simplequantitative method of selecting the composition of a multicomponentalloy for hydrogen storage and hydride electrode applications.Neglecting the small contribution due to M in Groups 1-4, the heat ofhydride formation can be calculated by the following equations:

The heat of hydride formation of an alloy in the first group ofmaterials having a composition represented by the formula:

    Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x

can be calculated by the following equation:

    H.sub.h =-5.0a-6.5b+0.67c-0.67d Kcal/mole H.               (4)

where a+b+c+d=3.

A suitable alloy in this group should have the value of H_(h) in therange between -3.5 and -9.0 Kcal/mole H, and preferably between -4.5 and-8.5 Kcal/mole H.

The heat of hydride formation of an alloy in the second group of thematerials having composition represented by the formula:

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x

can be calculated by the following equation:

    H.sub.h =-2.65a+1.66b-4.14c+2.98d-7.0 Kcal/mole H.         (5)

A suitable alloy in this group should have a value of H_(h) in the rangeof between -3.5 and -9.0 Kcal/mole H, and preferably between -4.5 and-8.5 Kcal/mole H.

The heat of hydride formation of an alloy in the third group of thematerials having a composition represented by the formula:

    Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c M.sub.x

can be calculated by the following equation:

    .[.H.sub.h =-2.65a-4.14+2.98C-7.0 Kcal/mole H..]. .Iadd.H.sub.h =2.65a-4.14b+2.98c-7.0Kcal/mole H..Iaddend.               (6)

A suitable alloy in this group should have a value of H_(h) in the rangeof between -3.5 and -9.0 Kcal/mole H, and preferably between -4.5 and-8.5 Kcal/mole H.

The heat of hydride formation of an alloy in the fourth group of thematerial having a composition represented by the formula:

    Ti.sub.a Mn.sub.b Ni.sub.c V.sub.d M.sub.x

can be calculated by the following equations:

    H.sub.h =(-15.0a-2.0b+2.0c-7.0d)/(a+b+c+d) Kcal/mole H.    (7)

A suitable alloy in this group should have a value of H_(h) in the rangebetween -3.5 and -9.0 Kcal/mole H, and preferably between -4.5 and -8.5Kcal/mole H.

The multicomponent alloy in accordance with the present invention can beprepared by induction heating, arc or plasma melting, under an inertatmosphere. A higher temperature as well as several remelting runs willbe useful to .[.obtian.]. .Iadd.obtain .Iaddend.a more homogeneousmaterial. A small amount of alkalai metal or alkaline earth can be usedas a deoxidizing agent during the melting process.

To store gaseous phase hydrogen, the active materials of the inventioncan be charged at 100 to 300 p.s.i. hydrogen after the air in the wholesystem has been evacuated. Moderate temperature of between 100 to 200degrees Centigrade will accelerate the hydriding or dehydriding process.It is .[.prefered.]. .Iadd.preferred .Iaddend.to first granulate thematerial into small particles in order to ensure complete activation ofthe material in the hydrogen.

For the electrochemical application, an electrode containing the activematerial of the present invention is first prepared. The electrode ismade in the following manner. The active material powder with or withoutbinder, such as pure nickel, aluminum or copper (up to 10 wt. %), iscold pressed onto a nickel grid or a nickel plated mild steel grid witha pressure of between 5 to 20 tons per square inch. The resultingelectrode may be subject to a sintering process (at 600 to 1100 degreesC. for 3 to 10 minutes under protective atmosphere) to enhance thestrength of the body structure. Finally, the electrode is activatedelectrochemically at an electric current density of up to 50 to 100 mA/grate (cathodic charging followed by anodic discharging) for a couple orseveral cycles in an alkaline solution. The electrode is then ready tocombine with a positive electrode such as an Ni-positive electrode foran electrochemical application.

.Iadd.The invention pertains to a material for hydrogen storage and ahydride electrode, said material comprising the composition formulaselected from the group consisting of:

    Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x M.sub.y

where M equals any of Al, Si, V, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.4,0.1≦b≦1.3, 0.25≦c≦1.95, 0.1≦d≦1.4, a+b+c+d=3, 0≦x≦0.2, and y>O wherein1.2≦Ti+Zr≦2.7;

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x,

and hydrides thereof,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd and rare earthmetals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.3,0.1≦b≦1.2, 0.1≦c≦1.3, 0.2≦d≦1.95, 0.5≦a+b+c+d≦2.9, 0≦x≦0.2, wherein0.2≦Ti+Zr≦0.80 and 0.1≦V≦1.4 and for x=0, and b=0.5, then a+c≠0.5.

The invention also pertains to a material for hydrogen storage and ahybride electrode, wherein said composition formula is:

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x

where M equals any of Al, Si, Fe, Co, Cu, Nb, Ag, Pd, and rare earthmetals, and where a, b, c, d, and x are defined by: 1.2≦a≦1.6,0.3≦b≦1.0, 0.1≦c≦1.7, 0.2≦d≦2.0, a+b+c+d=3, 0<x≦0.2.

The invention also pertains to a material for hydrogen storage and ahybride electrode, wherein said material having composition formulaconsisting of:

    Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x ;

and hydrides thereof, where M is selected from the group consisting ofAl, Si, V, Mn, Fe, Co, Cu, Nb, Ag, Pd and rare earth metals, and wherea, b, c, d, and x are defined by: 0.25≦a≦1.0, 0.2≦b≦1.0, 0.8≦c≦1.6,0.3≦d≦1.0, a+b+c+d=3, 3, 0≦x≦0.2, wherein 1.2≦Ti +Zr≦2.0.

The invention also pertains to a material for hydrogen storage and ahydride electrode, wherein said material having composition formulaconsisting of:

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x ;

and hydrides thereof, where M is selected from the group consisting ofAl, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earth metals, and where a,b, c, d, and x are defined by: 0.15≦a≦1.0, 0.15≦b≦1.0, 02.≦c≦1.0,0.4≦d≦1.7, 1.5≦a+b+c+d≦2.3 and 0≦x≦0.2, 0.35≦Ti+Zr≦0.8, 0.7≦V≦1.4 andfor x=0, b=0.5, then a+c≠0.5. .Iaddend.

EXAMPLE 1

A first group of materials is represented by the formula:

    Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x,

where M equals any of Al, Si, V, Mn, Fe, Co, Cu, Nb, and rare earthmetals, and where a, b, c, d and x are defined by: 0.1≦a≦1.4, 0.1≦b≦1.3,0.25≦c≦1.95, 0.1≦d≦1.4, a+b+c+d=3, and 0≦x≦0.2.

Alloys having compositions in this first group are given in Table 1.Proper amounts of pure metal elements were weighed, mixed, pressed intopellets, and then melted together by arc or induction heating underargon atmosphere. Small chunk samples ranging from 100 to 300 mg. weretested electrochemically in a 4M KOH solution. A nickel wire or nickelpositive electrode was used as the counter electrode. Theelectrochemical capacity at a 100 mA/g discharge rate of these alloysmeasured down to -700 mV versus an Hg/HgO reference electrode cut-offpotential is shown in Table 1. Material in this group have highcapacity, long life cycles and good rate capability. In this firstgroup, materials given in Table 1 also show the calculated heat ofhydride formation in the range of between -4.5 and -8.5 Kcal/mole H inagreement with the rules stated hereinabove.

EXAMPLE 2

A second group of materials is represented by the formula:

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, and rare earth metals,and where a, b, c, d, and x are defined by: 0.1≦a≦1.3, 0.1≦b≦1.2,0.1≦c≦1.3, 0.2≦d≦1.95, .[.0.4≦a+b+c+d≦2.9.]..Iadd.0.5≦a+b+c+d≦2.9.Iaddend., and 0≦x≦0.2.

Alloys having compositions in this second group were prepared and testedin accordance with the procedures described in Example 1. Some of theexperimental results are given in Table 1. Materials in this group havehigh capacity, long life cycles and good rate capability. In this secondgroup, materials listed in Table 1 also have the calculated heat ofhydride formation in the range of between -4.5 and -8.5 Kcal/mole H, inagreement with the rules stated hereinabove.

EXAMPLE 3

A third group of materials is represented by the formula:

    Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c M.sub.x,

where M equals any of Al, Si, Cr, Mn, Fe, Co, Cu, Nb, and rare earthmetals, and where a, b, c, and x are defined as: 0.1≦a≦1.3, 0.1≦b≦1.3,0.25≦c≦1.95, 0≦x≦0.2, and 0.6≦a+b+c≦2.9; for x=0 then a+b≠1 and0.24≦b≦1.3.

Alloys having compositions in this group were prepared and tested inaccordance with the procedure described in Example 1. Some of theexperimental results are also given in Table 1. In this third group,materials listed in Table 1 have the calculated heat of hydrideformation in the range between -4.5 and -8.5 Kcal/mole H, in agreementwith the rules stated hereinabove.

EXAMPLE 4

A fourth group of materials is represented by the formula:

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x,

where M equals any of Al, Si, Cr, Fe, Co, Cu, Nb, Zr, and rare earthmetals, and were a, b, c, d, and x are defined by: 0.1≦a≦1.6, 0.1≦b≦1.6,0.1≦c≦1.7, 0.2≦d≦2.0, a+b+c+d=3, and 0≦x≦0.2.

Alloys having compositions in this group were prepared and tested inaccordance with the procedures given in Example 1. Some of theexperimental results are given in Table 1. The cycle life and ratecapability of the alloys in this group are excellent. In this fourthgroup, materials shown in Table 1 have the calculated heat of hydrideformation in the range of between -4.5 and -8.5 Kcal/mole H, inagreement with the rules stated hereinabove.

                  TABLE 1                                                         ______________________________________                                        Electrochemical Capacity and Heat of Hydride Formation                        of Materials                                                                  Material Composition                                                                              Capacity.sup.1.                                                                         H.sub.h.sup.2.                                  ______________________________________                                        Group 1: Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x                          Ti.sub.0.3 Zr.sub.1.0 Ni.sub.1.4 Cr.sub.0.3                                                       280       -7.27                                           Ti.sub.0.4 Zr.sub.0.8 Ni.sub.1.4 Cr.sub.0.4                                                       290       -6.53                                           Ti.sub.0.5 Zr.sub.0.8 Ni.sub.1.2 Cr.sub.0.5                                                       300       -7.23                                           Ti.sub.0.5 Zr.sub.0.7 Ni.sub.1.3 Cr.sub.0.5                                                       290       -6.52                                           Ti.sub.0.5 Zr.sub.0.6 Ni.sub.1.4 Cr.sub.0.5                                                       275       -5.80                                           Ti.sub.0.5 Zr.sub.0.8 Ni.sub.1.1 Cr.sub.0.5 Mn.sub.0.1                                            265       -7.37                                           Group 2: Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x'         Ti.sub.0.4 Cr.sub.0.4 Zr.sub.0.2 Ni.sub.0.6 V.sub.1.4                                             295       -6.43                                           Ti.sub.0.3 Cr.sub.0.3 Zr.sub.0.5 Ni.sub.1.15 V.sub.0.45                                           268       -7.18                                           Ti.sub.0.3 Cr.sub.0.3 Zr.sub.0.4 Ni.sub.0.6 V.sub.1.4                                             330       -7.16                                           Ti.sub.0.35 Cr.sub.0.35 Zr.sub.0.5 Ni.sub.1.0 V.sub.0.8                                           285       -6.43                                           Ti.sub.0.3 Cr.sub.0.3 Zr.sub.0.5 Ni.sub.0.7 V.sub.1.2 Cu.sub.0.1                                  310       -7.28                                           Group 3: Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c M.sub.x'                    Ti.sub.0.6 Zr.sub.0.5 Ni.sub.1.1 V.sub.0.8                                                        310       -7.38                                           Ti.sub.0.7 Zr.sub.0.6 Ni.sub.1.3 V.sub.0.4                                                        290       -7.47                                           Ti.sub.0.7 Zr.sub.0.4 Ni.sub.1.3 V.sub.0.6                                                        280       -6.63                                           Ti.sub.0.65 Zr.sub.0.35 Ni.sub.1.30 V.sub.0.70                                                    305       -6.38                                           Ti.sub.0.3 Zr.sub.0.8 Ni.sub.1.3 V.sub.0.6                                                        275       -7.23                                           Ti.sub.0.5 Zr.sub.0.5 Ni.sub.1.1 V.sub.0.7 Cu.sub.0.2                                             250       -6.38                                           Group 4: Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x'                          Ti.sub.1.0 Mn.sub.0.5 V.sub.0.6 Ni.sub.0.9                                                        280       -6.13                                           Ti.sub.1.1 Mn.sub.0.5 V.sub.0.5 Ni.sub.0.9                                                        300       -6.40                                           Ti.sub.1.2 Mn.sub.0.45 V.sub.0.45 Ni.sub.0.9                                                      310       -6.75                                           Ti.sub.1.3 Mn.sub.0.39 V.sub.0.38 Ni.sub.0.93                                                     315       -7.03                                           Ti.sub.1.1 Mn.sub.0.5 V.sub.0.5 Ni.sub.0.9 Co.sub.0.1                                             280       -6.40                                           ______________________________________                                         .sup.1. mAh/g (at 100 mA/g)                                                   .sup.2. Kcal/mole H. The heats of hydride formation are calculated from       the equations 4-7, hereinabove.                                          

What is claimed is:
 1. A material for hydride hydrogen storage and ahydride electrode, said material comprising the composition formulaselected from the group consisting of:

    Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d M.sub.x H.sub.y

where M equals any of Al, Si, V, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.4,0.1≦b≦1.3, 0.25≦c≦1.95, 0.1≦d≦1.4, a+b+c+d=3, 0≦x≦0.2, and y<0.Iadd.wherein Ti+Zr≦1.2.Iaddend.;

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d M.sub.x,

.Iadd.and hydrides thereof.Iaddend., where M equals any of Al, Si, Mn,Co, Cu, Fe, Nb, Ag, Pd and rare earth metals, and where a, b, c, d, andx are defined by: 0.1≦a≦1.3, 0.1≦b≦1.2, 0.1≦c≦1.3, 0.2≦d≦1.95, .[.0.4.]..Iadd.0.5.Iaddend.≦a+b+c+d≦2.9, 0≦x≦0.2, and for x=0, and b=0.5, thena+c≠0.5 and .[.b≧0.25.]. .Iadd.wherein Ti+Zr≦0.80 and V≦1.4.[.;

    Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c M.sub.x,

where M equals any of Al, Si, Cr, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, b, c, and x are defined as: 0.1≦a≦1.3,0.1≦b≦1.3, 0.25≦c≦1.95, 0≦x≦0.2, and 0.6≦a+b+c≦2.9; and for X=0 thena+b≠1 and 0.24≦b≦1.3; and

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x,

where M equals any of Al, Si, Cr, Fe, Co, Cu, Nb, Zr, Ag, Pd, and rareearth metals, and were a, b, c, d, and x are defined by: 0.1≦a≦1.6,0.1≦b≦1.6, 0.1≦c≦1.7, 0.2≦d≦2.0, a+b+c+d=3, and 0≦x≦0.2, and for x=0then b+d≠0.75.].
 2. A hydride of the material .[.o.]. .Iadd.of.Iaddend.claim 1 comprising the composition formula selected from thegroup consisting of:

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b--c-d M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earthmetals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.3,0.1≦b≦1.2, .[..0.]. .Iadd.0.1.Iaddend.≦c≦1.3, 0.2≦d≦1.95, .[.0.4.]..Iadd.0.5 .Iaddend.≦a+b+c+d≦.[.2.4.]. .Iadd.2.9, .Iaddend.0≦x≦0.2 .[.,and for x=0, and b=0.5, then a+c≠0.5 and b≧0.25;

    Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c M.sub.x,

where M equals any of Al, Si, Cr, Fe, Co, Cu, Nb, Ag, Pd, and rare earthmetals, and were a, b, c, d and x are defined as: 0.1≦a≦1.3, 0.1≦b≦1.3,0.25≦c≦1.95, 0≦x≦0.2, and 0.6≦a+b+c≦2.9, and for x=0 then a+b≠1 and0.24≦b≦1.3: and

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x,

where M equals any of Al, Si, Cr, Fe, Co, Cu, Nb, Zr, Ag, Pd, and rareearth metals, and where a, b, c, d, and x are defined by: 0.1≦a≦1.6,0.1≦b≦1.6, 0.1≦c≦1.7, 0.2≦d≦2.0, a+b+c+d=3 and 0≦x≦0.2, and for x=0 thenb+d≠0.75.]..
 3. The material of claim 1 in the form of at least onehydride electrode for an electrochemical energy storage system.
 4. Amaterial as defined in claim 1, wherein said composition formula is

    Ti.sub.a Zr.sub.b Ni.sub.c Cr.sub.d H.sub.y,

where a, b, c, and d are defined by: 0.1≦a≦1.4, 0.1≦b≦1.3, 0.25≦c≦1.95,0.1≦d≦1.4, y>0 and a+b+c+d=3.
 5. The material of claim 4 in the form ofat least one hydride electrode for an electrochemical energy storagesystem.
 6. A material as defined in claim 1, wherein said compositionformula is:

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.d V.sub.3-a-b-c-d,

where a, b, c, and d, are defined by: 0.1≦a≦1.3, .[.0.25≦b≦1.2.]..Iadd.0.15≦b≦1.0, .Iaddend.0.1≦c≦1.3, 0.2≦d≦1.95.[., 0.4≦a+b+c+d≦2.9,and if b=0.5, then a+c≠0.5.]..
 7. A hydride of the material of claim 6.8. The material of claim .[.6.]. .Iadd.7 .Iaddend.in the form of atleast one hydride electrode for an electrochemical energy storagesystem. .[.
 9. A material as defined in claim 1, wherein saidcomposition formula is

    Ti.sub.a Zr.sub.b Ni.sub.c V.sub.3-a-b-c,

where a, b, and c are defined as: 0.1≦a≦1.3, 0.24≦b≦1.3, a+b-1,0.25≦c≦1.95, and 0.6≦a+b+c≦2.9..]. .[.10. A hydride of the material ofclaim 9..]. .[.11. The material of claim 10 in the form of at least onehydride electrode for an electrochemical energy storage system..]..[.12. A material as defined in claim 1, wherein said compositionformula is

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d,

were a, b, c, and d, are defined by: 1.6, 0.1≦a≦0.1≦b≦1.6, 0.1≦c≦1.7,0.2≦d≦2.0, b+d≠0.75 and a+b+c+d=3..]. .[.13. A hydride of the materialof claim 12..]. .[.14. The material of claim 13 in the form of at leastone hydride electrode for an electrochemical energy storage system..].15. A material .[.as defined in claim 1,.]. .Iadd.for hydrogen storageand a hydride electrode, .Iaddend.wherein said composition formula is

    Ti.sub.a Mn.sub.b V.sub.c Ni.sub.d M.sub.x,

where M equals any of Al, Si, .[.Cr,.]. Fe, Co, Cu, Nb, .[.Zr,.]. Ag,Pd, and rare earth metals, and .[.were.]. .Iadd.where .Iaddend.a, b, c,d, and x are defined by: 0.1≦a≦1.6, .[.0.1≦b≦1.6.]. .Iadd.0.3<b<1.0,.Iaddend.0.1≦c≦1.7, 0.2≦d≦2.0, a+b+c+d=3 and .[.0≦x≦0.2.]. .Iadd.0<x≦0.2and Ti+Zr≧1.2.Iaddend..
 16. A hydride of the material of claim
 15. 17.The material of claim 15 in the form of at least one hydride electrodefor an electrochemical energy storage system.
 18. A material as definedin claim 1, wherein said composition formula

    Ti.sub.a Cr.sub.a Zr.sub.c Ni.sub.d V.sub.3-2a-c-d M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earthmetals, and where a, c, d, and x are defined by: .[.0.25.]..Iadd.0.1.Iaddend.≦a≦1.2, 0.1≦c≦1.2, 0.2≦d≦1.95, 0.9≦2a+c+d≦2.8, and 0≦x≦0.2.
 19. A hydride of the material of claim
 18. 20. The material ofclaim .[.18.]. .Iadd.19 .Iaddend.in the form of at least one hydrideelectrode for an electrochemical energy storage system.
 21. A materialas defined in claim 1, wherein the composition formula is

    Ti.sub.a Cr.sub.b Zr.sub.1-a-b Ni.sub.d V.sub.2-d M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earthmetals, and where a, b, d, and x are defined by: 0.1≦a≦0.8, 0.1≦b≦0.8,0.25≦d≦1.95, 0≦x ≦0.2, .[.and for x=0, then b≠0.5 and b≧0.25.]..
 22. Ahydride of the material of claim
 21. 23. The material of claim .[.21.]..Iadd.22 .Iaddend.in the form of at least one hydride electrode for anelectrochemical energy storage system.
 24. A material as defined inclaim .[.22.]. .Iadd.21.Iaddend., wherein the composition formula is:

    Ti.sub.a Cr.sub.a Zr.sub.1-2a Ni.sub.d V.sub.2-d M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earthmetals, and where a, d, and x are defined by: 0.1≦a≦0.45, 0.25≦d≦1.95,0≦x≦0.2 .[.and when x=0 then a≧0.25.]..
 25. A hydride of the material ofclaim
 24. 26. The material of claim .[.19.]. .Iadd.25 .Iaddend.in theform of at least one hydride electrode for an electrochemical energystorage system.
 27. A material as defined in claim 1, wherein thecomposition formula is

    Ti.sub.a Cr.sub.a Zr.sub.c Ni.sub.2-c V.sub.1-2a M.sub.x,

where M equals any of Al, Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earthmetals, and where a, c, and x are defined by: 0.1≦a≦0.45, 0.2≦c≦1.2,0≦x≦0.2 .[.and if x=0, then a≧0.25.]..
 28. A hybride of the material ofclaim
 27. 29. The material of claim .[.27.]. .Iadd.28 .Iaddend.in theform of at least one hydride electrode for an electrochemical energystorage system. .[.30. A material as defined in claim 10, wherein thecomposition formula is

    Ti.sub.a Zr.sub.1.2+t-a-d Ni.sub.1.8-t V.sub.d,

where a, d, and t are defined as: 0.1≦a≦0.3 and 0.62≦a≦1.3, 0.2≦d≦1.8,0≦t≦1.55, 0≦t-a-d≦1.2 and -0.1≦a+d-t≦0.96. .]. .[.31. A hydride of thematerial of claim 30..]. .[.32. The material of claim 30 in the form ofat leat one hydride electrode for an electrochemical energy storagesystem..]. .[.33. A material as defined in claim 1, wherein thecomposition formula is

    Ti.sub.a Zr.sub.y-a Ni.sub.c V.sub.3-y-c M.sub.x,

where M equals any of Al, Si, Cr, Mn, Fe, Co, Cu, Nb, Ag, Pd, and rareearth metals, and where a, c, x, and y are defined as: 0.1≦a≦1.3,0.2≦c≦1.95, 0≦x≦0.2,and 0.7≦y≦1.6..]. .[.34. A hydride of the materialof claim 33..]. .[.35. The material of claim 33 in the form of at leastone hydride electrode for an electrochemical energy storage system..]..[.36. A material as defined in claim 1, wherein the composition formulais selected from the group consisting of:

    Ti.sub.a Zr.sub.b Ni.sub.2-b V.sub.1-a,

where a, and b are defined as: 0.1≦a≦0.8, 0.24≦b≦1.2, a+b≠1;

    Ti.sub.a Zr.sub.b Ni.sub.1-a V.sub.2-b,

where a, and b are defined as: 0.2≦a≦0.75, 0.24≦b≦1.2, a+b≠1; and

    Ti.sub.a Zr.sub.b Ni.sub.i-b V.sub.2-a,

where a, and b are defined as: 0.1≦a≦1.3, 0.24≦b≦0.75, a+b≠1..]. .[.37.A hydride of the material of claim 36..]. .[.38. The material of claim36 in the form of at least one hydride electrode for an electrochemicalenergy storage system..]. .[.39. A material as defined in claim 1,wherein the composition formula is

    Ti.sub.a Cr.sub.b Zr.sub.c Ni.sub.1.95-t V.sub.1.05+t-a-b-c,

where a, b, c and t are defined by: 0.1≦a≦1.2, 0.1≦b≦1.2, 0.1,≦c≦1.2,0≦t≦1.75, and for b=0.5, then a+c=0.5..]. .[.40. A hydride of thematerial of claim 39..]. .[.41. The material of claim 3 in the form ofat least one hydride electrode for an electrochemical energy storagesystem..]. .Iadd.42. A material for hydrogen storage and a hydrideelectrode selected from the group consisting of:Ti₀.3 Zr₁.0 Ni₁.4 Cr₀.3; Ti₀.5 Zr₀.8 Ni₁.2 Cr₀.5 ; Ti₀.5 Zr₀.8 Ni₁.2 Cr₀.5 Mn₀.1 ; and hydridesthereof. .Iaddend. .Iadd.43. A material for hydrogen storage and ahydride electrode selected from the group consisting of: Ti₀.4 Cr₀.4Zr₀.2 Ni₀.6 V₁.4 ; Ti₀.3 Cr₀.3 Zr₀.5 Ni₁.15 V₀.45 ; Ti₀.3 Cr₀.3 Zr₀.4Ni₀.6 V₁.4 ; Ti₀.3 Cr₀.3 Zr₀.5 Ni₀.7 V₁.2 Cu₀.1 ; and hydrides thereof..Iaddend. .Iadd.44. A material for hydrogen storage and a hydrideelectrode, wherein said material having composition formula consistingof:Ti_(a) Zr_(b) Ni_(c) Cr_(d) M_(x) ; and hydrides thereof, where M isselected from the group consisting of Al, Si, V, Mn, Fe, Co, Cu, Nb, Ag,Pd and rare earth metals, and where a, b, c, d, and x are defined by:0.25≦a≦1.0, 0.2≦b≦1.0, 0.8≦c≦1.6, 0.3≦d≦1.0, a+b+c+d=3, 0≦x≦0.2, whereinTi+Zr is≦1.2. .Iaddend. .Iadd.45. The material of claim 44 in the formof at least one hydride electrode for an electrochemical energy storagesystem. .Iaddend. .Iadd.46. A material for hydrogen storage and ahydride electrode, wherein said material having composition formulaconsisting of: Ti_(a) Cr_(b) Zr_(c) Ni_(d) V_(3-a-b-c-d) M_(x) ; andhydrides thereof, where M is selected from the group consisting of Al,Si, Mn, Co, Cu, Fe, Nb, Ag, Pd, and rare earth metals, and where a, b,c, d, and x are defined by: 0.15≦a≦1.0, 0.15≦b≦1.0, 0.2≦c≦1.0,0.4≦d≦1.7, 1.5 ≦a+b+c+d≦2.3 and 0≦x≦0.2, Ti +Zr≦0.8, V≦1.4 and for x=0,b=0.5 then a+c≠0.5. .Iaddend. .Iadd.47. The material of claim 46 in theform of at least one hydride electrode for an electrochemical energystorage system. .Iaddend.